GB820695A - Improvements in electric resistance welding - Google Patents

Abstract

820,695. Welding by pressure. ROBOTRON CORPORATION. Feb. 20, 1958 [May 20, 1957], No. 5548/58. Class 83 (4). In electric resistance welding the welding electrodes are pressed against the work, the timing operation of two separate timing means is simultaneously initiated and electrical energy is supplied from one of the timing means at the end of the time interval timed thereby to apply an additional electromagnetic pressing force on one of the electrodes and electrical energy is supplied from the other timing means at the end of the time interval timed thereby to cause flow of welding current through the electrodes. The work parts W1, W2, e.g. of vinyl coated steel or aluminium are arranged between a stationary lower electrode 10 on a base 11 and a movable upper electrode 12 connected to a piston-rod 13 of an hydraulic cylinder 14 and to an arm 16 on an armature 17 hinged at 19 to a U-shaped electromagnet 18 on base 11. The secondary 23 of a transformer 24 is connected to the electrodes and a winding 26 about one leg of the magnet is connected to the secondary 29 of a transformer 31. The primary windings 32, 34 are connected through time control means 33, 36 respectively to supply the electrodes and magnet winding from sources S1, S2. The control means are connected to a supply S3 through a control means 38 for simultaneously initiating the operation of the means 33, 36 and for controlling the application of hydraulic pressure by a solenoid valve 39. The control firstly causes the cylinder 14 to move the electrodes into contact with the work and then causes operation of control means 36, 33 which energize transformers 31, 24, one after the other during the same half cycle of supply current. The pressure on the work increases due to the pull of the magnet on the armature 17 and then the welding current of 5-25 millisecs. duration is caused to flow. The hydraulic means 14 may be replaced by air or mechanical means or the magnetic means may be used alone.